Power Conversion Device and Refrigeration Cycle Apparatus

The present application claims the benefit of priority to Japanese Patent Application No. 2024-191462, filed Oct. 31, 2024, which is incorporated herein by reference in its entirety.

The present disclosure relates to a power conversion device and a refrigeration cycle apparatus.

Patent Document 1 discloses a step-down chopper device that receives a three-phase AC as an input, converts the input current into a DC voltage via a rectifier, and steps down the converted voltage by switching a semiconductor switch. The step-down chopper device includes a smoothing capacitor on the output side, and a current on which a carrier ripple current is superimposed is generated due to the influence of the switching of the semiconductor switch. Therefore, if the carrier ripple current is allowed to flow out as it is, there is a possibility that peripheral devices are to be broken.

In view of this, the step-down chopper device of Patent Document 1 is provided with a capacitor (filter capacitor) for removing the carrier ripple current between a step-down converter and the rectifier. The step-down converter being configured by a semiconductor switch, a diode, and a reactor. The carrier ripple current generated in the step-down converter is absorbed by the capacitor disposed on the input side of the step-down converter, thereby reducing the carrier ripple current flowing out to the peripheral devices of the step-down chopper device.

4 1 5 Patent Document 1: Japanese Patent Application Laid-Open No. 2000-312478 Patent Document 2: International Publication No. WO2023/073870 Furthermore, the step-down chopper device of Patent Document 1 compares a modulated triangular wave Sgenerated on the basis of a voltage Vi of the filter capacitor with an output signal Sbased on an output voltage Vo of the smoothing capacitor, thereby generating a pulse width modulation (PWM) signal Sbased on the comparison result to control the semiconductor switch. That is, the step-down chopper device of Patent Document 1 performs feedback control of the output voltage Vo on the basis of the output voltage Vo being the voltage of the smoothing capacitor, and the voltage Vi of the filter capacitor. In addition, by reducing the ripple of the output voltage Vo, the step-down chopper device of Patent Document 1 can reduce the electrostatic capacitance of the filter capacitor on the input side of the step-down converter.

Patent Document 2 discloses that if the electrostatic capacitance of a filter capacitor, which is a capacitor disposed between a rectifier and a power conversion unit that converts DC power into AC power, is made too large, an input current to the filter capacitor and a charging/discharging current of the filter capacitor have a shape resembling “rabbit ears”, that is, a spike shape. This spike shaped current flows out of the rectifier to the power supply, causing the power supply current to have a spike shape. That is, the power supply current is greatly distorted, and the power supply harmonics are deteriorated.

The present disclosure aims to reduce a carrier ripple current and to reduce an outflow of the carrier ripple current to a power supply.

A power conversion device includes a rectifier circuit to convert an input voltage of a three-phase AC input from AC input terminals into a DC voltage, a converter to output an output voltage set to a set voltage value from the DC voltage output from the rectifier circuit, a smoothing capacitor connected between a positive-side converter output terminal and a negative-side converter output terminal of the converter from which the output voltage is output, a filter disposed between the AC input terminals and the converter and including a filter capacitor, and a controller to control the converter. The converter includes a switching element that is controlled with PWM by a control signal generated on the basis of a carrier wave and an on-duty command. The controller designates any one of a voltage of the filter, a current of the filter, a ripple component in the voltage of the filter, and a ripple component in the current of the filter as a filter focusing target, and generates the on-duty command for reducing a difference between a detection value of the filter focusing target and a target value of the filter focusing target.

In the power conversion device of the present disclosure, since the filter having the filter capacitor is disposed between the AC input terminals and the converter, and the controller generates the on-duty command for reducing the difference between the detection value and the target value in the filter focusing target that is any one of the voltage of the filter, the current of the filter, a ripple component in the voltage of the filter, and a ripple component in the current of the filter, it is possible to reduce the carrier ripple current and to reduce the outflow of the carrier ripple current to the power supply.

1 FIG. 2 FIG. 3 FIG. 4 FIG. 1 FIG. 5 FIG. 6 FIG. 5 FIG. 7 FIG. 8 FIG. 9 FIG. 10 FIG. 11 FIG. 12 FIG. 50 1 7 is a diagram showing a configuration of a power conversion device according to Embodiment 1, andis a diagram showing a configuration of a first controller according to Embodiment 1.is a diagram showing a duty ratio, andis a diagram showing a configuration of a rectifier circuit of.is a diagram showing a configuration of a second controller according to Embodiment 1, andis a diagram showing a configuration of a phase change feedback control unit of.is a diagram showing a configuration of a third controller according to Embodiment 1,is a diagram showing a configuration of a fourth controller according to Embodiment 1, andis a diagram showing a configuration of a fifth controller according to Embodiment 1.is a diagram showing an operation waveform of a power conversion device of a comparative example. Each ofandis a diagram showing an operation waveform of the power conversion device according to Embodiment 1. The power conversion deviceaccording to Embodiment 1 converts three-phase AC input power input from a three-phase AC power supplyinto DC power and supplies the DC power to a load.

50 2 1 55 55 55 91 2 6 64 64 91 10 91 7 57 57 r s t p n p n. The power conversion deviceincludes a rectifier circuitfor converting input power, i.e., an input voltage and an input current, of the three-phase AC power supplyfrom AC input terminals,, and, to DC power i.e., a DC voltage and a DC current, a converterfor outputting an output voltage Vo set to a set voltage value, from the DC voltage output from the rectifier circuit, a smoothing capacitorconnected between a positive-side output terminal(positive-side converter output terminal) and a negative-side output terminal(negative-side converter output terminal) in the converterfrom which the output voltage Vo is output, and a controllerfor controlling the converter, and supplies to the loadDC power having the output voltage Vo set to the set voltage value from output terminalsand

91 3 4 5 91 91 91 91 91 6 64 64 91 6 7 3 3 3 a b c p n a 1 FIG. The converterincludes a switching element, a diode, and a control reactor. In Embodiment 1, a step-down converterwill be described as an example of the converter. In Embodiment 2, a step-up converterand a step-up/step-down converterwill be described as examples of the converter. The smoothing capacitoris connected between the positive-side DC output terminaland the negative-side DC output terminalof the step-down converter, and the smoothing capacitorstabilizes the output voltage Vo. The DC power having the output voltage Vo is supplied to the load. As the switching element, for example, a power semiconductor element such as an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), or the like is used. In, an example of an IGBT is shown. The switching elementincludes a transistor Tr being the IGBT, and a diode Di. The diode Di is connected in anti-parallel to the transistor Tr being the IGBT. When a MOSFET is used as the transistor Tr of the switching element, the collector and emitter of the IGBT are interpreted as the drain and source of the MOSFET.

1 FIG. 21 FIG. 20 FIG. 7 7 In, a DC variable resistor is shown as an example of the load. The loadis not limited to the DC variable resistor, and may be, for example, a constant current load or a constant power load. Alternatively, a motor (refer to) may be connected after the power is inversely converted to AC power by using an inverter (refer to). In this case, the combination of the inverter and the motor can be regarded as a DC variable resistor.

90 9 1 63 63 91 90 1 3 91 50 90 55 55 55 3 8 2 9 90 91 91 90 90 91 91 90 8 90 8 p n r s t a a A filterincluding a filter capacitoris disposed between the three-phase AC power supplyand DC input terminalsandof the converter. More specifically, the filteris disposed between the three-phase AC power supplyand the switching elementof the converter. That is, the power conversion deviceincludes the filterbetween the AC input terminals,, and, and the switching element. Here, a filter reactoris disposed right after the rectifier circuit, and a filter capacitoris disposed in the subsequent stage. The filterserves to reduce a carrier ripple current generated in the convertersuch as the step-down converterand to reduce an outflow of the carrier ripple current to the power supply. The role of the filtercan also be described as follows. The filterserves to reduce distortion of a power supply current Ips due to the carrier ripple current generated in the convertersuch as the step-down converterand to reduce current distortion of the power supply current Ips having a shape resembling “rabbit ears”, that is, a spike shape. Although an example in which the filterincludes the filter reactorwill be described in Embodiment 1, the filtermay not include the filter reactor.

10 90 90 90 90 17 17 18 17 17 18 17 17 18 17 1 3 17 18 17 17 90 18 90 17 90 18 90 17 90 18 90 17 90 18 90 The controllerdesignates any one of a voltage of the filter, a current of the filter, a ripple component in the voltage of the filter, or a ripple component in the current of the filteras a filter focusing target, and generates an on-duty command D* that reduces the difference between a detection value of the filter focusing targetand a command value of a filter focusing target command, which is a target value of the filter focusing target. The on-duty command D* is a command that reduces the difference between the detection value of the filter focusing targetand the command value of the filter focusing target command, which is the target value of the filter focusing target, and is generated so as to reduce the difference between the detection value of the filter focusing targetand the command value of the filter focusing target command, which is the target value of the filter focusing target. The on-duty command D* is a command used to generate a control signal sigfor PWM control of the switching element. When the on-duty command D* is updated multiple times, the difference between the detection value of the filter focusing targetand the command value of the filter focusing target command, which is the target value of the filter focusing target, becomes smaller than that at the time of starting the control or at the time of changing an operating condition to be close to zero. In Embodiment 1, an example in which the filter focusing targetis the voltage of the filterand the filter focusing target commandis a command of the voltage of the filter, and an example in which the filter focusing targetis the ripple component in the voltage of the filterand the filter focusing target commandis a command of the ripple component in the voltage of the filterwill be described. An example in which the filter focusing targetis the current of the filterand the filter focusing target commandis a command of the current of the filter, and an example in which the filter focusing targetis the ripple component in the current of the filterand the filter focusing target commandis a command of the ripple component in the current of the filterwill be described in Embodiment 4.

50 2 19 19 19 19 19 19 19 19 61 19 19 61 19 19 61 19 19 19 19 19 62 19 19 19 62 2 62 62 1 55 55 55 50 71 71 71 55 55 55 71 71 71 71 a f a b c d e f r a b s c d t e f a c e p b d f n p n r s t r s t r s t r s t The power conversion deviceof Embodiment 1 will be described in detail. The rectifier circuitis a bridge rectifier circuit including, for example, six diodesto. Diodesandconnected in series are for an arm of an r-phase of the three-phase AC, diodesandconnected in series are for an arm of an s-phase of the three-phase AC, and diodesandconnected in series are for an arm of a t-phase of the three-phase AC. An AC input terminalis connected to a connection point of the diodesand, an AC input terminalis connected to a connection point of the diodesand, and an AC input terminalis connected to a connection point of the diodesand. Cathodes of the diodes,, andare connected to a positive-side DC output terminal, and anodes of the diodes,, andare connected to a negative-side DC output terminal. The rectifier circuitoutputs a DC output voltage Va from the DC output terminalsand. The three-phase AC power supplyis connected to the AC input terminals,, andof the power conversion devicethrough power lines,, and. The reference signs for the power lines connected to the AC input terminals,, andare collectively denoted by a reference numeral, and,, andare used for distinction.

61 61 61 2 55 55 55 50 1 61 61 61 2 71 55 55 55 2 50 55 55 55 71 1 2 1 55 55 55 r s t r s t r s t r s t r s t r s t 1 FIG. The AC input terminals,, andof the rectifier circuitare connected to the AC input terminals,, andof the power conversion device, respectively. Input power P, that is, an interphase voltage Vac and the power supply current Ips of each phase are input from the three-phase AC power supplyto the AC input terminals,, andof the rectifier circuitvia the power linesand the AC input terminals,, and. The interphase voltage Vac and the power supply current Ips are an input voltage and an input current, respectively, which are input to the rectifier circuitof the power conversion device. The interphase voltage Vac is a voltage between two phases of the three-phase AC input from the AC input terminals,, and. The interphase voltage Vac is generally referred to as a line-to-line voltage among power linesof the three-phase AC power supply. The rectifier circuitconverts the input power P, that is, an input voltage (interphase voltage Vac) and an input current (power supply current Ips) of the three-phase AC power supplyinput from the AC input terminals,, andinto DC power, that is, a DC voltage (output voltage Va) and a DC current.shows the interphase voltage Vac between the s-phase and the t-phase. There are also interphase voltages Vac between the r-phase and the s-phase and between the r-phase and the t-phase.

90 91 6 2 6 57 57 50 7 62 2 57 50 73 8 90 3 5 91 62 2 57 50 73 p n p p p n n n. The filter, the converter, and the smoothing capacitorare sequentially arranged on the downstream side of the rectifier circuit, and the output voltage Vo of the smoothing capacitoris output from the output terminalsandof the power conversion deviceto the load. The DC output terminalof the rectifier circuitis connected to the output terminalof the power conversion deviceby a positive-side linein which the filter reactorof the filter, and the switching elementand the control reactorthat are in the converterare inserted. The DC output terminalof the rectifier circuitis connected to the output terminalof the power conversion deviceby a negative-side line

90 8 9 55 55 55 91 50 90 2 55 55 55 8 90 55 55 55 9 62 68 62 2 68 9 63 91 8 62 8 73 68 9 63 91 68 9 73 r s t r s t r s t p p p p p p p p p n n. 1 FIG. 1 FIG. The filterincludes the filter reactorand the filter capacitor, and is disposed between the AC input terminals,, and, and the converterof the power conversion device.shows an example in which the filteris disposed downstream of the rectifier circuitconnected to the AC input terminals,, and. The filter reactorof the filtershown inis disposed closer to the AC input terminals,, andthan the filter capacitor, and is connected between the DC output terminaland a positive-side capacitor terminal, the DC output terminalbeing a positive-side rectifier circuit output terminal of the rectifier circuit, the positive-side capacitor terminalbeing one end of the filter capacitorconnected to the DC input terminalbeing the positive-side converter input terminal of the converter. More specifically, one end of the filter reactoris connected to the DC output terminalof the rectifier circuit, and the other end of the filter reactoris connected by the positive-side lineto the positive-side capacitor terminalbeing one end of the filter capacitor, and the DC input terminalof the converter. A negative-side capacitor terminalbeing the other end of the filter capacitoris connected to the negative-side line

91 63 63 64 64 58 91 91 3 63 3 4 5 5 64 4 73 63 64 73 3 58 1 29 10 58 1 3 p n p n a p p n n n n The converterincludes the DC input terminalsand, the DC output terminalsand, and a control terminal. In the step-down converter, which is an example of the converter, the collector of the switching elementis connected to the DC input terminal, and the emitter of the switching elementis connected to the cathode of the diodeand one end of the control reactor. The other end of the control reactoris connected to the DC output terminal. The anode of the diodeis connected to the negative-side line, and is connected to the DC input terminaland the DC output terminalby the negative-side line. The gate of the switching elementis connected to the control terminal. A control signal sig, whose voltage value is changed by a drive circuiton the basis of a gate signal command G* output from the controller, is input to the control terminal. The control signal sigis a signal for controlling an ON state and an OFF state of the switching elementby, for example, PWM control.

10 5 91 50 10 11 11 10 2 2 2 6 11 2 9 11 2 11 5 12 10 3 12 5 5 63 91 5 12 3 4 5 10 9 a a c a c a a b b c c p The controllercontrols a control reactor current IL, which is a current of the control reactorof the step-down converter, and/or the output voltage Vo as aimed. Information of each of sensors to be detected by the power conversion deviceis input to the controller. In this case, voltages detected by the voltage sensortois input to the controlleras voltage sensor information sigto sig. The volage sensor information sigis a voltage of the smoothing capacitordetected by the voltage sensor, the volage sensor information sigis a voltage of the filter capacitordetected by the voltage sensor, and the volage sensor information sigis the interphase voltage Vac detected by the voltage sensor. The control reactor current IL being the current of the control reactordetected by a current sensoris input to the controlleras current sensor information sig. The current sensorfor detecting the control reactor current IL of the control reactoris disposed on the input side of the control reactor, that is, on the side of the DC input terminalof the converterwith respect to the control reactor. More specifically, the current sensoris disposed between the emitter of the switching elementand the cathode of the diode, and one end of the control reactor. When the feedback control by the controller, which will be described later, is performed on a filter capacitor voltage Vin being the voltage of the filter capacitor, ripple of the power supply current Ips can be reduced.

1 3 1 3 3 29 3 The control signal sigis an operation signal for operating the switching elementin a predetermined state. In general, the control signal sigcorresponds to the ON/OFF signal for controlling the switching elementto be in the ON state or the OFF state. Here, the signal is input to the switching elementvia the drive circuitfor operating the switching element.

91 6 5 91 2 6 3 5 11 12 6 5 11 12 a a a a a In order to control the step-down converter, voltage information of the smoothing capacitorand current information of the control reactorare required. Here, the voltage information and the current information required for controlling the step-down converterare the voltage sensor information sigof the smoothing capacitorand the current sensor information sigof the control reactorthat are to be detected by using the voltage sensorand the current sensor. However, the voltage information of the smoothing capacitorand the current information of the control reactorare not necessarily detected by using the voltage sensorand the current sensor, and estimated values may be used instead.

10 10 6 6 2 FIG. 5 FIG. 7 FIG. 8 FIG. 9 FIG. Configurations of the first to fifth controllersare shown in,,,, and. The first to fifth controllersdetermine a smoothing capacitor voltage command Vdc*, which is a voltage command for controlling the output voltage Vo being the voltage of the smoothing capacitor, to an arbitrary value. The output voltage Vo being the voltage of the smoothing capacitoris denoted as a smoothing capacitor voltage Vdc, as appropriate.

10 1 6 6 21 22 32 28 a The first to fifth controllersobtain a voltage deviation ΔV, which is a deviation between a command value of the smoothing capacitor voltage command Vdc* of the smoothing capacitorand a detection value of the smoothing capacitor voltage Vdc, which is a detection value of the output voltage Vo of the smoothing capacitor, by a subtractor. The voltage deviation AVI is input to a voltage feedback control unitthat performs voltage feedback control. The voltage feedback control is often performed by using proportional-integral control (PI control). The voltage feedback control may be performed by using proportional-integral-derivative control (PID control), proportional-derivative control (PD control), or the like, or may be performed by using another combination of proportional control (P control), integral control (I control), and derivative control (D control). The P control for outputting output data that multiplies the input data by K times is performed by a proportional output unit. The I control for outputting output data that integrates input data is performed by an integrator M. The D control for outputting output data that differentiates input data is performed by a differentiator. Note that, in the figures, “feedback” of the voltage feedback control unit and the current feedback control unit is denoted as “FB”.

91 91 9 91 9 3 91 a a a In Embodiment 1, since the converteris the step-down converter, the smoothing capacitor voltage command Vdc* needs to be set to be smaller than the voltage of the filter capacitorinput to the step-down converter, that is, the filter capacitor voltage Vin. When the smoothing capacitor voltage command Vdc* is set to be larger than the voltage of the filter capacitor, the switching elementis always in the ON state, resulting in the same as the normal rectifying operation, and the output voltage from the step-down converteris the same as the voltage input thereto, and cannot be stepped up to the set voltage of the smoothing capacitor voltage command Vdc*.

22 5 5 5 21 22 23 10 23 10 33 23 10 23 1 21 10 33 23 5 21 23 10 33 10 1 23 33 b d d An output of the voltage feedback control unitis output as a current command IL* for the control reactor. A current deviation AI, which is a deviation between a command value of the current command IL* for the control reactorand a detection value of the control reactor current IL of the control reactor, is obtained by a subtractorin a subsequent stage of the voltage feedback control unit. The current deviation AI is directly input to a current feedback control unitthat performs current feedback control. In the first, second, third, and fifth controllers, the current deviation AI is directly input to the current feedback control unit. In the fourth controller, the current deviation AI is indirectly input to a feedback control unitthat has the function of the current feedback control unit. The current feedback control often uses the PI control. The current feedback control may use the PID control, the PD control, or the like similarly to the voltage feedback control, and may use another combination of the P control, the I control, and the D control. In the first, second, third, and fifth controllers, the output of the current feedback control unitis output as a first command B* input to a subtractorthat generates the on-duty command D*. In the fourth controller, the output of the feedback control unithaving the function of the current feedback control unitis output as a fifth command B* input to the subtractorthat generates the on-duty command D* The current feedback control of the current feedback control unitin the first, second, third, and fifth controllersand the current feedback control of the feedback control unitin the fourth controllerare for making the power supply current Ips of the three-phase AC power supplyin a rectangular wave shape, that is, a rectangular wave current. The current feedback control by the current feedback control unitand the feedback control unitneed to be designed to be as highly responsive as possible in order to make the power supply current Ips have a rectangular wave shape. As for the current control, it is possible to perform the control with higher accuracy by using repetitive control.

24 31 10 10 10 24 2 9 9 21 2 24 24 32 28 c 2 FIG. In order to reduce the ripple of the power supply current Ips, a damping feedback control unitand a phase change feedback control unitare added in the first to fifth controllers. First, the first controllerwill be described. In the first controller, the damping feedback control unitis added to reduce the ripple of the power supply current Ips. A voltage deviation AVthat is a deviation between a command value of a filter capacitor voltage command Vin* being a voltage command of the filter capacitorand a detection value of the filter capacitor voltage Vin of the filter capacitoris obtained by a subtractor. The voltage deviation AVis input to the damping feedback control unitfor reducing the ripple. In the feedback control for reducing the ripple, the PI control is often used as in the voltage feedback control and current feedback control. In the feedback control for reducing the ripple, the PID control, the PD control, or the like may be used, and another combination of the P control, the I control, and the D control may be possible, as in the voltage feedback control and current feedback control. Note that, in the damping feedback control unitof, an example is shown in which the proportional output unit, the integrator M, and the differentiatorare included. Further, in the figures, “feedback” of the damping feedback control unit, the phase change feedback control unit, and the feedback control unit is denoted as “FB”

9 15 1 Here, a method of generating the filter capacitor voltage command Vin* of the filter capacitorwill be described. Phase voltages Vr, Vs, and Vt having an amplitude Vam and a power supply phase θ are calculated by a phase voltage calculation unitfrom analog voltage signals of the interphase voltage Vac of the three-phase AC power supply. As a calculation method, a method called an enhanced Phase Looked Loop (ePLL) can be used.

15 1 2 The amplitude Vam and the power supply phase θ may be derived using a zero crossing signal of the interphase voltage Vac. When only the zero crossing from the negative signal to the positive signal is detected in the interphase voltage Vac, the zero crossing signal is input to the phase voltage calculation unitonce in one cycle of the three-phase AC. When the time between the zero crossings is a time Tand the current time from the immediately preceding zero crossing is a time T, the power supply phase θ being a phase angle can be calculated as in Equation (1). The unit shall be radians [rad].

The amplitude Vam can be calculated as in Equation (2) by integrating the absolute value of the interphase voltage Vac between the zero crossings and taking the average value.

π/2 is the coefficient for converting from the average to the root mean square value. Thus, by using Equation (1) and Equation (2) from the zero crossings, the amplitude Vam for the phase voltages Vr, Vs, and Vt and the power supply phase θ can be derived.

9 The amplitude Vam of the phase voltages Vr, Vs, and Vt and the power supply phase θ can be calculated using only the zero crossing signal, without analog detection of the interphase voltage Vac. In this case, the amplitude Vam for the phase voltages Vr, Vs, and Vt can be derived using an average value of the voltage of the filter capacitor, Vinave, by Equation (3).

1 K1 is a gain and should be typically set to “K1=π/3.” When a resistive component in a power supply impedance etc. of the three-phase AC power supplyis large, K1 should be finely adjusted, for example, slightly increased.

24 FIG. The phase voltages Vr, Vs, and Vt including the calculated amplitude Vam and the power supply phase θ are stored in a memory (refer to) according to Equation (4) to Equation (6).

From the phase voltages Vr, Vs, and Vt stored in the memory, one command value for the filter capacitor voltage command Vin* can be generated by using a maximum phase voltage Vmax and a minimum phase voltage Vmin as shown in Equation (7).

The maximum phase voltage Vmax is a maximum phase voltage among the phase voltages Vr, Vs, and Vt. When expressed by a MAX function for obtaining a maximum value, the maximum phase voltage Vmax is MAX (Vr, Vs, Vt). The minimum phase voltage Vmin is a minimum phase voltage among the phase voltages Vr, Vs, and Vt. When expressed by a MIN function for obtaining a minimum value, the minimum phase voltage Vmin is MIN (Vr, Vs, Vt).

10 15 10 16 At a time when the controllergenerates each command value of the filter capacitor voltage command Vin*, the phase voltage calculation unitcalculates the phase voltages Vr, Vs, and Vt of the three phases of the three-phase AC from the input interphase voltage Vac. Vmax-Vmin is a phase voltage deviation ΔVph obtained by subtracting the minimum phase voltage Vmin from the maximum phase voltage Vmax. The sign of the phase voltage deviation ΔVph is positive or negative because the sign of the maximum phase voltage Vmax and the minimum phase voltage Vmin is positive or negative. At the time when the controllergenerates each command value of the filter capacitor voltage command Vin*, the filter voltage command generation unitcalculates the maximum phase voltage Vmax and the minimum phase voltage Vmin from the values of the phase voltages Vr, Vs, and Vt that are input, and generates the phase voltage deviation ΔVph that is calculated by subtracting the minimum phase voltage Vmin from the maximum phase voltage Vmax, as the filter capacitor voltage command Vin*.

9 24 2 24 2 2 24 10 9 27 10 9 27 21 9 24 9 FIG. c When a DC component of the filter capacitor voltage Vin of the filter capacitorremains in the damping feedback control unititself, that is, when the DC component of the filter capacitor voltage Vin remains in the voltage deviation AV, there will be a case where the damping feedback control unitcannot generate an appropriate second command B*. In this case, the voltage deviation AVshould be input to the damping feedback control unitvia a high-pass filter. Further, the fifth controllershown inmay be configured by extracting a voltage ripple component ΔVin being a ripple component of the filter capacitor voltage Vin from the filter capacitor voltage Vin of the filter capacitorvia the high-pass filter. In the fifth controller, the voltage ripple component ΔVin being the ripple component of the filter capacitor voltage Vin is extracted from the filter capacitor voltage Vin of the filter capacitorvia the high-pass filter, and a ripple component deviation ΔVrp that is a deviation between a command value of a voltage ripple component command ΔVin* and the voltage ripple component ΔVin is obtained using the subtractor, the voltage ripple component command ΔVin* being a command of the ripple component of the filter capacitor voltage Vin in the filter capacitor. The ripple component deviation ΔVrp is input to the damping feedback control unitfor reducing the ripple.

10 2 24 1 23 21 1 6 6 2 17 17 35 1 36 2 21 37 1 1 2 2 10 35 1 1 21 22 21 23 36 2 2 21 24 d d a b c 2 FIG. The controllergenerates the on-duty command D* by subtracting the second command B* generated by the damping feedback control unitfrom the first command B* generated by the current feedback control unitwith the subtractor. The first command B* is a command that reduces the difference between the detection value of the smoothing capacitor voltage Vdc, which is the voltage of the smoothing capacitor, and the command value of the smoothing capacitor voltage command Vdc*, which is the target value of the voltage of the smoothing capacitor. The second command B* is a command that reduces the difference between the detection value of the filter focusing targetand the target value of the filter focusing target. The on-duty command D* is generated from each of outputs of two systems, that is, a first system control unitthat generates the first command B*, and a second system control unitthat generates the second command B*. Therefore, the subtractorthat generates the on-duty command D* can be described as an on-duty command generation unit. The first command B* can be described as a first system command C*, and the second command B* can be described as a second system command C*. In the first controllershown in, the first system control unitthat generates the first command B*, that is, the first system command C* includes the subtractor, the voltage feedback control unit, the subtractor, and the current feedback control unit. The second system control unitthat generates the second command B*, that is, the second system command C* includes the subtractorand the damping feedback control unit.

10 26 25 26 26 26 2 FIG. The controllerinputs the on-duty command D* and a carrier waveto a carrier comparison unit. As the carrier wave, a triangular wave from 5 kHz to 20 kHz is often used. Althoughshows an example in which the carrier waveis a triangular wave, the carrier wavemay be a sawtooth wave.

25 26 26 25 3 26 25 3 3 FIG. The carrier comparison unitcompares the on-duty command D* with the carrier wave, and when the on-duty command D* is larger than the carrier wave, the carrier comparison unitoutputs a gate signal command G* for turning the switching elementin the ON state. Conversely, when the on-duty command D* is smaller than the carrier wave, the carrier comparison unitoutputs the gate signal command G* for turning the switching elementin the OFF state. The gate signal command G* is a command having a duty ratio D as shown in. The gate signal command G* is typically generated using a PWM function installed on a microcomputer, or generated by a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), or the like.

3 FIG. 1 26 The duty ratio D will be described. A pulse wave of the gate signal command G* as a digital signal is shown in. The duty ratio D is obtained by dividing a high period Th, which is a period during which the gate signal command G* is a high voltage (digital value of 1), by a switching period Tsw of the gate signal command G*. That is, the duty ratio Dis expressed by Th/Tsw. The duty ratio D of the control signal sig, which is a digital signal with the changed voltage value, is similarly expressed in Th/Tsw. The switching period Tsw is the period of the carrier wave.

3 1 10 91 a When the switching elementis driven by the control signal sigbased on the gate signal command G* output from the controller, the step-down convertercan be controlled so as to output a desired voltage value.

10 91 22 23 2 FIG. The control block diagram of the first controllershown inis an example of a control method for controlling the converter, and this control method does not necessarily need to be used, and the voltage control system, that is, the voltage feedback control unit, may be omitted, or the current control system, that is, the current feedback control unit, may be omitted.

10 10 10 15 16 10 10 24 31 10 31 31 49 490 32 41 43 44 10 36 31 49 490 91 31 46 46 32 49 490 5 FIG. 7 FIG. 8 FIG. 9 FIG. 2 FIG. 5 FIG. 6 FIG. i i a b i Next, the second to fifth controllerswill be described. The second to fifth controllersare improved versions of the first controller. Note that, in,,, and, the phase voltage calculation unitand the filter voltage command generation unitdescribed inare omitted. The second controllershown indiffers from the first controllerin that the damping feedback control unitis replaced with the phase change feedback control unit. Components that differ from those in the first controllerwill be mainly described.shows a configuration of the phase change feedback control unit. The phase change feedback control unitincludes a data input terminal, a data output terminal, the proportional output unit, a memory unit, an input selection controller, and an output selection controller. The second controller, in the second system control unit, includes the phase change feedback control unitthat performs proportional processing and integral processing on an input data Din input from a first terminal, which is the data input terminal, and outputs an output data Do whose phase is changed by a predetermined set phase a, from the second terminal, which is the data output terminal. When a frequency for controlling the converteris defined as a control frequency Fct and a number obtained by dividing the control frequency Fct by a power supply frequency Fps being a frequency of the three-phase AC is defined as a division number Ndv, the phase change feedback control unitincludes the same number of integrators M as the division number Ndv, a selectorthat selects an integrator M to which data (input data Din) is input, a selectorthat selects an integrator M that outputs data (output data Do) that is different in phase from the input data Din by the set phase a, and the proportional output unitin a data path between the first terminal (data input terminal) and the second terminal (data output terminal).

41 41 1 41 41 41 41 41 40 41 46 46 0 1 2 n-1 0 1 2 n-1 0 1 2 n-1 0 n-1 6 FIG. a b. The memory unithas a total of N integrators M corresponding to the power supply phases θ. Specifically, the memory unitincludes a total of N integrators M, M, M, . . . , M, each provided for each power supply phase θ. In, four integrators M, M, M, and Mare specifically shown. The integrators are collectively denoted by M, and when distinguishing them, M, M, M, and Mare used. For example, consider a case where the control frequency Fct, which is the frequency of the control cycle, is 18 kHz, and the power supply frequency Fps of the three-phase AC power supplyis 60 Hz. The division number Ndv equals 18 k/60, which is 300. In other words, the angle of one cycle is divided into 300 angle ranges with respect to the power supply phase θ, and 300 integrators Mto Mare installed in the memory unit. The memory unitstores the data integrated by each integrator M. Note that it may be considered that each integrator M in the memory unitperforms the integration when the input data Din is input and stores the integrated data. In this case, each integrator M in the memory unitincludes a memory to store the integrated data. Here, the output data Do output from the integrator M is data integrated and stored in the memory unit. Therefore, each integrator M corresponds to a power source phases θ of 1.2 degree (360 degrees/300), and each integrator M integrates the input data Din shifted by the phase deviationbeing a deviation of 1.2 degree in the power source phase θ. The memory unitfurther includes the selectorand the selector

41 31 32 32 32 41 32 41 41 32 49 49 6 FIG. i o Before inputting data into the memory unitof the phase change feedback control unit, the proportional output unitis placed to adjust the magnitude of the input data Din. The proportional output unitis placed to prevent the compensation amount, that is, the output data Do, from becoming too large or too small.shows an example where the proportional output unitis placed before the memory unit, but the proportional output unitcan also be placed within the memory unitor after the memory unit. In other words, the proportional output unitonly needs to be placed in the data path between the first terminal (data input terminal) and the second terminal (data output terminal).

31 32 43 2 44 43 46 46 44 46 46 10 0 n-1 0 n-1 a a b b The phase change feedback control unitincludes the proportional output unitand the integrators M, and performs feedback control, and thus it can be said to be an improved version of a PI controller that performs the PI control. The input selection controlleraccumulates the voltage deviation AVin any one of the integrators Mto Mcorresponding to the power supply phase θ. The output selection controllercauses any one of the integrator Mto Mcorresponding to the power supply phase θ that has been changed by the set phase a to output a compensation amount, that is, the output data Do. The input selection controlleroutputs, to the selector, a selection signal ssa for selecting an integrator M to which the input data Din is input. The selectorselects the integrator M to which the input data Din is input on the basis of the selection signal ssa. The output selection controlleroutputs, to the selector, a selection signal ssb for selecting an integrator M that outputs the output data Do. The selectorselects the integrator M that outputs the output data Do on the basis of the selection signal ssb. The set phase a needs to consider two types of delays: a delay caused by the controllerand a delay caused by the integration of the input data Din.

10 1 The delay caused by the controlleris a dead-time delay, which is due to a calculation time delay of the controller, such as a microcontroller. This typically corresponds to one control cycle (/control frequency Fct).

An example of the delay caused by the integration of the input data Din will be described in relation to the reactor current. Let an inductance of the reactor be L, a reactor current of this reactor be iL, and a reactor voltage of this reactor be VL. The reactor current iL is expressed by Equation (8).

46 44 43 2 31 b The reactor current iL is expressed by integration of the reactor voltage VL. Therefore, even when the reactor voltage VL is output, a certain period of time is required until the reactor voltage VL is reflected as a current value, and a delay corresponding to one control cycle needs to be taken into consideration. As described above, the two types of delays correspond to two control cycles. Therefore, the timing when the output data Do is output from the selector, that is, the timing when the output selection controllerselects an integrator M, is set to be advanced by two control cycles compared to the timing when the input selection controllerselects an integrator M to which the input data Din is input. In other words, the integrator M corresponding to θ−2×Δθ, which is the phase advanced by 2× Δθ of the current power supply phase θ, outputs the integrated and stored data as the output data Do. Therefore, the set phase a is 2×Δθ. The set phase a has been described using the reactor current iL and the reactor voltage VL as an example, but since the delay caused by the integration is considered, the type of input data Din is not limited to the reactor voltage VL and may be the filter capacitor voltage Vin, voltage deviation ΔV, etc. The set phase a may be set on the basis of the data obtained from an actual operation in response to the input data Din input into the phase change feedback control unit.

31 2 21 41 3 10 1 1 35 3 2 36 31 21 37 2 1 10 31 5 FIG. c d The phase change feedback control unitshown ininputs the voltage deviation ΔVoutput from the subtractoras the input data Din and outputs the output data Do output from the integrator M of the memory unitcorresponding to the phase changed from the phase of the input data Din by the set phase a as the third command B*. The second controllergenerates the first command B* as the first system command C* by the first system control unitand generates the third command B* as the second system command C* by the second system control unitincluding the phase change feedback control unit. The subtractor, which is the on-duty command generation unit, generates the on-duty command D* by subtracting the second system command C* from the first system command C*. The operation after the generation of the on-duty command D* is the same as that of the first controller. By using the phase change feedback control unit, the deviation becomes smaller each control cycle, and the filter capacitor voltage Vin can finally converge to the command value, that is, the filter capacitor voltage command Vin*.

10 10 10 10 31 24 10 10 10 7 FIG. Further, the first controllermay be modified to look like the third controllershown in. The third controllerdiffers from the first controllerin that the phase change feedback control unitis located in parallel with the damping feedback control unit. Even with the third controller, the deviation becomes smaller each control cycle, and the filter capacitor voltage Vin can finally converge to the command value, that is, the filter capacitor voltage command Vin*. The main components that differ from the first controllersand the second controllerswill be described below.

24 31 2 24 3 31 21 36 10 21 24 31 21 2 21 24 31 24 2 2 31 3 2 21 2 3 4 4 2 36 e c e c e The damping feedback control unitand the phase change feedback control unitare arranged in parallel so that the same input is input, and the second command B* being the output of the damping feedback control unit, and the third command B* being the output of the phase change feedback control unitare input to a subtractor. The second system control unitin the third controllerhas the subtractor, the damping feedback control unit, the phase change feedback control unit, and the subtractor. The voltage deviation ΔVgenerated by the subtractoris input to the damping feedback control unitand the phase change feedback control unit. The damping feedback control unitoutputs the second command B* based on the voltage deviation ΔV. The phase change feedback control unitoutputs the third command B* being the output data Do, which is based on the voltage deviation ΔVbeing the input data Din. The subtractergenerates a deviation between the second command B* and the third command B* as the fourth command B*. The fourth command B* is the second system command C* generated by the second system control unit.

10 1 1 35 4 2 36 24 31 21 37 2 1 d The third controllergenerates the first command B* as the first system command C* by the first system control unit, and generates the fourth command B* as the second system command C* by the second system control unitincluding the damping feedback control unitand the phase change feedback control unit. The subtractorbeing the on-duty command generation unitsubtracts the second system command C* from the first system command C* to generate the on-duty command D*

10 10 10 10 35 23 36 24 37 33 31 33 23 24 10 10 8 FIG. 8 FIG. Further, the first controllermay be modified to look like the fourth controllershown in. The fourth controlleris different from the first controllerin that the first system control unitdoes not include the current feedback control unit, the second system control unitdoes not include the damping feedback control unit, and the on-duty command generation unitincludes the feedback control unitand the phase change feedback control unit, the feedback control unithaving the functions of the current feedback control unitand the damping feedback control unit, that is, the current feedback control function and the damping feedback control function. Differences from the first controllerand the second controllerwill be mainly described. Note that the “feedback” of the feedback control unit inis denoted as “FB”

35 21 22 21 21 1 36 21 32 2 21 2 32 2 37 21 33 31 21 33 31 5 33 3 31 21 21 1 2 2 33 31 33 5 31 3 21 5 3 a b b c c a e d d e a d The first system control unitincludes the subtractor, the voltage feedback control unit, and the subtractor, and generates the current deviation AI generated by the subtractoras the first system command C*. The second system control unitincludes the subtractorand the proportional output unitthat multiplies the voltage deviation ΔVgenerated by the subtractorby K, and generates a voltage deviation ΔVgenerated by the proportional output unitas the second system command C*. The on-duty command generation unitincludes the subtractor, the feedback control unit, the phase change feedback control unit, and the subtractor. The feedback control unitand the phase change feedback control unitare arranged in parallel so that the same input is input, and the fifth command B* being the output of the feedback control unit, and the third command B* being the output of the phase change feedback control unitare input to the subtractor. The subtractorgenerates a composite deviation ΔQ, which is a deviation between the current deviation ΔI being the first system command C* and the voltage deviation ΔVbeing the second system command C*. The composite deviation ΔQ is input to the feedback control unitand the phase change feedback control unit. The feedback control unit, which has the current feedback control function and the damping feedback control function, generates a fifth command B* based on the composite deviation ΔQ. The phase change feedback control unitgenerates the third command B* being the output data Do based on the composite deviation ΔQ being the input data Din. The subtractorgenerates the on-duty command D* as a deviation between the fifth command B* and the third command B*

10 1 35 2 2 36 37 2 1 a The fourth controllergenerates the current deviation AI as the first system command C* by the first system control unitand generates the voltage deviation ΔVas the second system command C* by the second system control unit. The on-duty command generation unitgenerates the on-duty command D* based on the composite deviation ΔQ, which is obtained by subtracting the second system command C* from the first system command C*.

10 33 31 33 31 32 8 FIG. In the fourth controllershown in, an example is shown in which both the feedback control unitand the phase change feedback control unitare included. However, it is also possible to include only one of the feedback control unitand the phase change feedback control unit. The proportional output unitis configured to adjust a control amount for damping control only.

10 10 10 17 90 18 90 10 36 2 21 24 21 90 21 9 FIG. c c c Furthermore, the first controllermay be modified to look like the fifth controllershown in. The fifth controlleris an example where the filter focusing targetis a ripple component of the voltage in the filter, and the filter focusing target commandis a command for the ripple component of the voltage in the filter. Components that differ from those in the first controllerwill be mainly described. The second system control unit, which generates the second system command C*, includes the subtractorand the damping feedback control unit. The subtractorgenerates the ripple component deviation A Vrp as the deviation between the voltage ripple component ΔVin, which is the ripple component in the voltage of the filterbeing the filter capacitor voltage Vin, and a command value of the voltage ripple component command ΔVin*, which is a target value of the voltage ripple component ΔVin. Specifically, the subtractorgenerates the ripple component deviation ΔVrp by subtracting the voltage ripple component ΔVin from the voltage ripple component command ΔVin*.

27 21 c Since the filter capacitor voltage Vin contains a DC component, the voltage ripple component ΔVin is extracted through the high-pass filter. The voltage ripple component ΔVin is input to the subtractor. Since it is desirable that the filter capacitor voltage Vin does not oscillate, the command value of the voltage ripple component ΔVin, that is, the command value of the voltage ripple component command ΔVin* should be set to zero.

24 2 2 10 1 1 35 2 2 36 21 37 2 1 10 d The damping feedback control unitoutputs the second command B* as the second system command C* based on the ripple component deviation ΔVrp. The fifth controllergenerates the first command B* as the first system command C* by the first system control unit, and generates the second command B* as the second system command C* by the second system control unit. The subtractorbeing the on-duty command generation unitsubtracts the second system command C* from the first system command C* to generate the on-duty command D*. The operation after the generation of the on-duty command D* is the same as that of the first controller.

10 17 90 18 90 10 17 18 10 10 10 5 FIG. 5 FIG. 7 FIG. 8 FIG. An example of the controllerin which the filter focusing targetis the voltage ripple component ΔVin in the filter capacitor voltage Vin of the filter, and the filter focusing target commandis the voltage ripple component command ΔVin*, which is the command for the ripple component of the filter capacitor voltage Vin of the filter, has been described in the fifth controllershown in. However, the filter focusing targetand the filter focusing target commandin the second controllershown in, the third controllershown in, and the fourth controllershown inmay also be the voltage ripple component ΔVin and the voltage ripple component command ΔVin*. In this case as well, the ripple component deviation ΔVrp becomes smaller each control cycle, and the voltage ripple component ΔVin of the filter capacitor voltage Vin can ultimately converge to the command value, that is, the voltage ripple component command A Vin*.

50 50 50 50 10 50 36 10 FIG. 11 FIG. 12 FIG. 11 FIG. 12 FIG. Next, operation waveforms of the power conversion deviceof Embodiment 1 will be described in comparison with the comparative example.shows an operation waveform of the power conversion device in the comparative example, andandshow operation waveforms of the power conversion deviceof Embodiment 1. Note that the operation waveform of the power conversion deviceof Embodiment 1 is denoted as the operation waveform of Example 1 as appropriate. The diagrams of the operation waveforms shown inandare those of the power conversion deviceincluding the first controller. The power conversion device of the comparative example differs from the power conversion deviceof Embodiment 1 in that it does not include the second system control unit.

10 FIG. 10 FIG. 10 FIG. 11 FIG. 12 FIG. 10 FIG. 82 82 36 24 82 23 First, the operation waveform of the comparative example shown inwill be described.shows a current characteristicof the power supply current Ips. The power supply current Ips is the current of one phase of the three-phase AC. In, the horizontal axis represents time [s], and the vertical axis represents power supply current Ips [A]. Note that the horizontal and vertical axes inandare the same as the horizontal and vertical axes in. The current characteristicof the power supply current Ips in the comparative example shows that the power supply current Ips fluctuates greatly, and the current in a manner resembling “rabbit ears” flows as the power supply current Ips. Since the power conversion device of the comparative example does not include the second system control unitthat has the damping feedback control unitfor the ripple reduction, the current characteristicof the power supply current Ips in the comparative example shows large ripple in the power supply current, and only with the normal current feedback control unit, the distortion of the current waveform remains significantly.

11 FIG. 12 FIG. 11 FIG. 81 81 36 24 a b Next, the operation waveforms of Example 1 will be described.shows a current characteristicof the power supply current Ips, andshows a current characteristicof the power supply current Ips. The operation waveform of Example 1 shown inhas less waveform distortion compared to the comparative example. Therefore, it can be confirmed that the control performance of the second system control unitthat includes the damping feedback control unitfor the ripple reduction is effective.

12 FIG. 12 FIG. 90 90 8 9 9 8 90 26 90 The operation waveform of Example 1 shown inis the waveform obtained when the characteristic of the filteris optimized. The operation waveform inis for the case where the filterincludes the filter reactorand the filter capacitor. The resonant frequency Fre depending on the filter capacitorand the filter reactorin the filteris set to be 18 times or more the frequency of the three-phase AC (power supply frequency Fps) and equal to or lower than half of the frequency of the carrier wave(carrier frequency Fca). The resonant frequency Fre [Hz] in the filterof Example 1 can be expressed by Equation (9).

8 9 Here, Lf is the filter inductance of the filter reactor, and Cf is the filter capacitance of the filter capacitor.

81 81 b a 12 FIG. 11 FIG. The current characteristicof the power supply current Ips inhave less waveform distortion compared to the current characteristicof the power supply current Ips inand the current can be considered as a rectangular wave current.

90 90 8 9 91 90 90 90 a A method of setting the parameters of the filter, that is, the filter inductance Lf and the filter capacitance Cf, will be described. First, in consideration of the removal of the carrier ripple current, the filterincluding the filter reactorand the filter capacitoris operated as a low pass filter to remove the carrier ripple current generated in the step-down converter. The resonant frequency Fre of the filtershould be set to be lower than the carrier frequency Fca so that attenuation is effective in the band of the carrier frequency Fca. For example, when the resonant frequency Fre is set to be equal to or lower than half the carrier frequency Fca, the current passing through the filterin the band of the carrier frequency Fca can be attenuated. Therefore, in order to remove the carrier ripple current, the upper limit of the resonant frequency Fre of the filtershould be half of the carrier frequency Fca.

2 90 8 90 90 90 82 90 9 9 Next, a method of reducing the distortion of the power supply current Ips will be considered. When the AC power is converted into the DC power by using the rectifier circuit, if the resonant frequency Fre of the filteris low, a spike-shaped current including harmonics such as “rabbit ears” is generated in the power supply current Ips. If the filter inductance Lf of the filter reactoris increased as a countermeasure against this, the power supply current Ips is rounded to have a rectangular waveform. However, when the power supply current Ips is made to have a rectangular waveform by taking measures only with the filter inductance Lf, the filter inductance Lf becomes too large, and thus the size of the filterincreases and the cost of the filteralso increases. Therefore, as another method of reducing the distortion of the power supply current Ips, there is a method of increasing the resonant frequency Fre of the filter. The resonant frequency Fre is preferably higher than the power supply frequency Fps, but if the resonant frequency Fre is approximately 18 times or more the power supply frequency Fps, the power supply current Ips can be regarded as a rectangular wave current. When the resonant frequency Fre are 18 times or more the power supply frequency Fps, unlike the current characteristicof the power supply current Ips in the comparative example, a plurality of current rises can be eliminated even if there is some fluctuation during one cycle of the power supply current Ips of each phase. Therefore, in order to reduce the distortion of the power supply current Ips and to make the power supply current Ips a rectangular wave current, the lower limit of the resonant frequency Fre of the filtershould be 18 times the power supply frequency Fps. If the filter capacitance Cf of the filter capacitoris too large, the power supply current Ips does not become a rectangular wave current. Therefore, a film capacitor having a small filter capacitance Cf and a large current rating should be used as the filter capacitor.

90 90 50 The resonant frequency Fre of the filtershould satisfy both of a condition that is equal to or lower than half the carrier frequency Fca and a condition that is equal to or higher than 18 times the power supply frequency Fps. For example, the parameters of the filterin the power conversion deviceaccording to Embodiment 1, that is, the filter inductance Lf and the filter capacitance Cf are Lf=200 μH and Cf=10 μF. The resonant frequency Fre can be calculated from Equation (9). In this case, the resonant frequency Fre is about 3600 Hz, which is about one fourth of the carrier frequency Fca and 60 times the power supply frequency Fps.

2 90 2 90 2 Although the output of the rectifier circuitincludes a ripple containing components of a multiple of 6 (6 times, 12 times, 18 times, or the like) of the power supply frequency Fps, the resonant frequency Fre of the filteris preferably high in order to improve the characteristics of the rectifier circuit. When the resonant frequency Fre of the filteris increased from six times the power supply frequency Fps to three times further thereof, that is, to 18 times the power supply frequency Fps, the output of the rectifier circuitcan obtain a favorable characteristic.

50 50 5 The power conversion deviceof Embodiment 1 can prevent the breakage of the peripheral devices by reducing the outflow of the carrier ripple current. Further, by reducing the distortion of the power supply current Ips, component losses can be reduced, and a component with a small current rating can be applied. In addition, the power conversion deviceof Embodiment 1 can reduce the current distortion, so that the inductance of the control reactorcan be reduced.

21 21 22 23 24 31 33 15 16 25 10 98 99 21 21 22 23 24 31 33 15 16 25 98 99 98 99 a e a e 24 FIG. 24 FIG. Note that functions of the subtractorsto, the voltage feedback control unit, the current feedback control unit, the damping feedback control unit, the phase change feedback control unit, the feedback control unit, the phase voltage calculation unit, the filter voltage command generation unit, and the carrier comparison unit, which are functional blocks of the controller, may be implemented by a processorand a memoryshown in.is a diagram showing an example of a hardware configuration for implementing the functions of the controller by digital computation. In this case, the subtractorsto, the voltage feedback control unit, the current feedback control unit, the damping feedback control unit, the phase change feedback control unit, the feedback control unit, the phase voltage calculation unit, the filter voltage command generation unit, and the carrier comparison unitare implemented by the processorexecuting a program stored in the memory. In addition, a plurality of the processorsand a plurality of the memoriesmay execute each function in cooperation with each other.

3 4 3 3 4 3 4 3 4 Note that the switching elementmay be a silicon semiconductor element formed using silicon or a wide bandgap semiconductor element formed using a wide bandgap semiconductor material having a bandgap larger than that of silicon. Examples of the wide bandgap semiconductor material include silicon carbide (SiC), gallium nitride material such as gallium nitride (GaN), and diamond. As a semiconductor material for the diode, silicon or a wide bandgap semiconductor material can be used as in the case of the switching element. When the switching elementand the diodeare semiconductor elements formed of a wide bandgap semiconductor material, that is, wide bandgap semiconductor elements, the switching speed and the operation speed are higher and the loss such as the switching loss is smaller than those of silicon semiconductor elements. Further, the wide bandgap semiconductor elements have higher voltage resistance and higher heat resistance than the silicon semiconductor elements. Therefore, when the switching elementand the diodeare the wide bandgap semiconductor elements, a heat sink or the like that is a cooler for the switching elementand the diodecan be downsized, or the heat sink or the like may be unnecessary.

50 2 55 55 55 91 2 6 64 64 91 90 55 55 55 91 9 10 91 91 3 1 26 10 90 90 17 17 18 50 90 9 55 55 55 91 10 18 17 90 90 r s t p n r s t r s t As described above, the power conversion deviceof Embodiment 1 includes the rectifier circuitthat converts the input voltages (interphase voltage Vac) of the three-phase AC input from the AC input terminals,, andinto the DC voltage, the converterthat outputs the output voltage Vo set to the set voltage value from the DC voltage output from the rectifier circuit, the smoothing capacitorconnected between the positive-side converter output terminal (DC output terminal) and the negative-side converter output terminal (DC output terminal) of the converterfrom which the output voltage Vo is output, the filterdisposed between the AC input terminals,, andand the converterand including the filter capacitor, and the controllerthat controls the converter. The converterincludes the switching elementthat is controlled with PWM by the control signal siggenerated on the basis of the carrier waveand the on-duty command D*. The controllerdesignates the voltage of the filter(filter capacitor voltage Vin) or the ripple component of the voltage of the filter(voltage ripple component ΔVin) as the filter focusing target. It generates the on-duty command D* for reducing the difference between the detection value of the filter focusing targetand the target value of the filter focusing target (filter focusing target command). In the power conversion deviceof Embodiment 1, with this configuration, since the filterincluding the filter capacitoris disposed between the AC input terminals,, and, and the converter, and the controllergenerates the on-duty command D* for reducing the difference between the detection value and the target value (filter focusing target command) in the filter focusing target, which is the voltage of the filter(filter capacitor voltage Vin) or the ripple component (voltage ripple component ΔVin) in the voltage of the filter, it is possible to reduce the carrier ripple current and to reduce the outflow of the carrier ripple current to the power supply.

13 FIG. 14 FIG. 13 FIG. 50 50 91 91 91 50 b c is a diagram showing a configuration of a power conversion device according to Embodiment 2, andis a diagram showing a configuration of another example of the converter of. The power conversion deviceof Embodiment 2 is different from the power conversion deviceof Embodiment 1 in that the converteris a step-up converteror a step-up/step-down converter. The differences from the power conversion deviceof Embodiment 1 will be mainly described.

13 FIG. 14 FIG. 91 91 91 91 91 91 5 63 5 3 4 4 64 5 4 73 3 73 63 64 73 3 58 58 1 29 10 1 3 12 5 63 5 b c b p p p n n n n p shows an example in which the converteris the step-up converter.shows an example in which the converteris a step-up/step-down converter. In the step-up converter, which is an example of the converter, one end of the control reactoris connected to the positive DC input terminal, and the other end of the control reactoris connected to the collector of the switching elementand the anode of the diode. The cathode of the diodeis connected to the positive-side DC output terminal. The control reactorand the diodeare inserted in the positive-side line. The emitter of the switching elementis connected to the negative-side line, and is connected to the DC input terminaland the DC output terminalsby the negative-side line. The gate of the switching elementis connected to the control terminal. The control terminalreceive the control signal sigwhose voltage value is changed by the drive circuiton the basis of the gate signal command G* output from the controller. The control signal sigis a signal for controlling the ON state and the OFF state of the switching elementby, for example, PWM control. The current sensorfor detecting the control reactor current IL being the current of the control reactoris disposed between the DC input terminaland one end of the control reactor.

90 91 91 90 90 91 91 90 8 90 8 b b The filterserves to reduce a carrier ripple current generated in the convertersuch as the step-up converterand to reduce the outflow of the carrier ripple current to the power supply. Further, the role of the filtercan also be described as follows. The filterserves to reduce distortion of the power supply current Ips due to the carrier ripple current generated in the convertersuch as the step-up converter, and to reduce the current distortion of the power supply current Ips in a shape resembling “rabbit ears”, that is, a spike shape. In Embodiment 2, an example in which the filterincludes the filter reactorwill be described, however, the filtermay not include the filter reactor.

10 10 6 91 91 9 91 b b. The first to fifth controllerin Embodiment 1 can be applied to the controllerin Embodiment 2. Since the same control configuration as that of Embodiment 1 can be used, a detailed description thereof will be omitted. However, the smoothing capacitor voltage command Vdc* being the voltage command for controlling the output voltage Vo, which is the voltage of the smoothing capacitor, is determined to be an arbitrary value. Since the converteris the step-up converter, the smoothing capacitor voltage command Vdc* should be set to be larger than the voltage of the filter capacitorinput to the step-up converter

91 5 91 91 90 90 b b a The input side of the step-up converteris the control reactor, and a waveform such as a triangular wave is input to the step-up converter, and therefore, the generated carrier ripple current is smaller than that of the step-down converter. However, the filterand the method of selecting the parameters of the filterdescribed in Embodiment 1 are effective in reducing the carrier ripple current and the outflow of the carrier ripple current to the power supply.

13 FIG. 91 3 3 91 91 91 91 91 b a c b a. Note that, althoughshows an example in which the step-up converterhas a two-level configuration, it is needless to say that the number of switching elementscan be increased to have a three-level configuration, etc. in which a plurality of the switching elementsare connected in series. Similarly, the step-down converterdescribed in Embodiment 1 may be set to be the three-level. The convertermay be the step-up/step-down converterhaving both the function of the step-up converterand the function of the step-down converter

91 3 3 5 4 4 3 4 5 91 5 3 4 91 91 3 63 3 4 5 5 3 4 4 64 4 3 73 63 64 73 3 5 4 73 3 58 3 58 c a b a b a a a b b b c a p a a b b b p a b n n n n a b p a a b b. 14 FIG. 13 FIG. The step-up/step-down convertershown inincludes two switching elementsand, the control reactor, and two diodesand. The configuration including the switching element, the diode, and the control reactoris the same as that of the step-down converterdescribed in Embodiment 1. The configuration including the control reactor, the switching element, and the diodeis the same as that of the step-up convertershown in. In the step-up/step-down converter, the collector of the switching elementis connected to the DC input terminal, and the emitter of the switching elementis connected to the cathode of the diodeand one end of the control reactor. The other end of the control reactoris connected to the collector of the switching elementand the anode of the diode. The cathode of the diodeis connected to the DC output terminal. The anode of the diodeand the emitter of the switching elementare connected to the negative-side line, and are connected to the DC input terminaland the DC output terminalby the negative-side line. The switching element, the control reactor, and the diodeare inserted into the positive-side line. The gate of the switching elementis connected to a control terminal, and the gate of the switching elementis connected to a control terminal

58 58 1 29 10 1 29 1 10 58 1 29 2 10 58 58 58 1 1 1 10 1 2 12 5 3 5 12 73 1 3 3 91 3 3 91 3 3 91 3 3 a b a a b b a b a b a p a b c b a c a b c 1 FIG. 13 FIG. 14 FIG. The control terminalsandreceive a control signal sigwhose voltage value is changed by the drive circuiton the basis of the gate signal command G* output from the controller. To be more specific, the control signal swhose voltage value is changed by the drive circuiton the basis of the gate signal command G* output from the controlleris input to the control terminal. The control signal swhose voltage value is changed by the drive circuiton the basis of the gate signal command G* output from the controlleris input to the control terminal. The reference signs for the control signals input to the control terminalsandare collectively denoted by sig, and the reference signs sand sare used for distinction. The reference signs for the gate signal commands output from the controllerare collectively denoted by G*, and are distinguished by G* and G*. The current sensorfor detecting the control reactor current IL being the current of the control reactoris disposed between the emitter of the switching elementand one end of the control reactor. The control reactor current IL detected by the current sensoris also the current flowing through the positive-side line, and thus is also the positive-side line current Ip, as with the control reactor current IL shown inand. The control signal sigis a signal for controlling the ON state and the OFF state for the switching elementsandby, for example, PWM control. When the step-up/step-down converteris caused to function as a step-down converter, the switching elementis turned in the OFF state, and the switching elementis controlled to be in the ON state and the OFF state. When the step-up/step-down converteris caused to function as a step-up converter, the switching elementis turned in the ON state, and the switching elementis controlled to be in the ON state and the OFF state. Note that, althoughshows an example in which the step-up/step-down converterhas the two-level configuration, it is needless to say that the number of switching elementscan be increased to have a three-level configuration, etc. in which a plurality of the switching elementsare connected in series.

50 50 50 5 50 50 90 9 55 55 55 91 10 18 17 90 90 r s t The power conversion deviceof Embodiment 2 can prevent the breakage of the peripheral devices by reducing the outflow of the carrier ripple current, as in the power conversion deviceof Embodiment 1. Further, by reducing the distortion of the power supply current Ips, component losses can be reduced, and a component with a small current rating can be applied. In addition, the power conversion deviceof Embodiment 2 can reduce the current distortion, so that the inductance of the control reactorcan be reduced. In the power conversion deviceof Embodiment 2 as in the power conversion deviceof Embodiment 1, since the filterincluding the filter capacitoris disposed between the AC input terminals,, and, and the converter, and the controllergenerates the on-duty command D* that reduces the difference between the detection value and the target value (filter focusing target command) in the filter focusing target, which is the voltage of the filter(filter capacitor voltage Vin) or the ripple component (voltage ripple component ΔVin) in the voltage of the filter, it is possible to reduce the carrier ripple current and to reduce the outflow of the carrier ripple current to the power supply.

15 FIG. 16 FIG. 8 90 2 55 55 55 91 8 55 55 55 2 50 50 8 55 55 55 2 50 r s t r s t r s t is a diagram showing a configuration of a first power conversion device according to Embodiment 3, andis a diagram showing a configuration of a second power conversion device according to Embodiment 3. In Embodiment 1 and Embodiment 2, the examples are shown in which the filter reactorof the filteris disposed between the rectifier circuitconnected to the AC input terminals,, and, and the converter. However, the filter reactormay be disposed between the AC input terminals,, and, and the rectifier circuit. The power conversion deviceof Embodiment 3 is different from the power conversion devicesof Embodiment 1 and Embodiment 2 in that the filter reactoris disposed between the AC input terminals,, and, and the rectifier circuit. The following description will focus on differences from the power conversion devicesof Embodiment 1 and Embodiment 2.

50 8 55 61 2 8 55 61 2 8 55 61 2 90 8 9 2 8 15 FIG. 15 FIG. r r s s t t In a first power conversion deviceof Embodiment 3 shown in, a first filter reactoris connected between the AC input terminaland the AC input terminalbeing a rectifier circuit input terminal of the rectifier circuit. Similarly, a second filter reactoris connected between the AC input terminaland the AC input terminalbeing a rectifier circuit input terminal of the rectifier circuit, and a third filter reactoris connected between the AC input terminaland the AC input terminalbeing a rectifier circuit input terminal of the rectifier circuit. The filterof Embodiment 3 includes three filter reactorsand the filter capacitor, with the rectifier circuitinterposed between the reactors and the filter capacitor. The three filter reactorsshown inare on the AC side (alternating current side), and therefore can be referred to as AC reactors.

8 90 8 8 Although a total of three filter reactorsare required on the AC side because three-phase AC is input, the LC filtercan be effectively operated even in such a configuration. Note that the value of the filter inductance Lf of the filter reactoris doubled because the current passes through the filter reactortwice in the forward and backward directions.

50 45 8 50 8 55 55 55 61 61 61 2 8 45 45 16 FIG. r s t r s t Further, a second power conversion deviceof Embodiment 3 may have a configuration as shown in. The reactor of a common mode choke coilto be installed for noise removal can be used as the filter reactor. In the second power conversion deviceof Embodiment 3, the filter reactorsare connected between the AC input terminals,, and, and the AC input terminals,, andbeing the rectifier circuit input terminals of the rectifier circuit, and the three filter reactorscorresponding to the respective phases of the three-phase AC constitute the common mode choke coil. The common mode choke coilis normally effective for the common mode, but can be used for the normal mode because it has a slight inductance.

50 50 50 5 50 90 8 9 55 55 55 91 8 55 55 55 9 2 10 18 17 90 90 r s t r s t The power conversion deviceof Embodiment 3 can prevent the breakage of the peripheral devices by reducing the outflow of the carrier ripple current, similarly to the power conversion devicesof Embodiment 1 and Embodiment 2. Furthermore, by reducing the distortion of the power supply current Ips, component losses can be reduced, and a component with a small current rating can be applied. In addition, the power conversion deviceof Embodiment 3 can reduce the current distortion, so that the inductance of the control reactorcan be reduced. In the power conversion deviceof Embodiment 3, the filterincluding the three filter reactorsand the filter capacitoris disposed between the AC input terminals,, and, and the converter, and more specifically, the three filter reactorsare disposed closer to the AC input terminals,, andthan the filter capacitor, with the rectifier circuitinterposed between the filter reactors and filter capacitor, and the controllergenerates the on-duty command D* that reduces the difference between the detection value and the target value (filter focusing target command) in the filter focusing target, which is the voltage of the filter(filter capacitor voltage Vin) or the ripple component (voltage ripple component ΔVin) in the voltage of the filter. Therefore, it is possible to reduce the carrier ripple current and to reduce the outflow of the carrier ripple current to the power supply.

17 FIG. 18 FIG. 19 FIG. 50 17 2 90 17 50 50 17 50 is a diagram showing a configuration of a power conversion device according to Embodiment 4.is a diagram showing a configuration of a first controller according to Embodiment 4, andis a diagram showing a configuration of a second controller according to Embodiment 4. In the power conversion deviceof Embodiment 1 to Embodiment 3, an example of using the filter capacitor voltage Vin as the filter focusing targetis shown, but a rectifier circuit current Iin, which is output from the rectifier circuitand input to the filter, may also be used as the filter focusing target. The power conversion deviceof Embodiment 4 differs from the power conversion deviceof Embodiment 1 to Embodiment 3 in that it uses the rectifier circuit current Iin as the filter focusing target. The differences from the power conversion deviceof Embodiment 1 to Embodiment 3 will be mainly described.

50 11 12 90 50 12 12 12 5 12 50 5 2 2 17 FIG. b b a b a The power conversion deviceof Embodiment 4 shown indoes not include a voltage sensorfor detecting the filter capacitor voltage Vin but includes a current sensorfor detecting the rectifier circuit current Iin flowing into the filter. The power conversion deviceof Embodiment 4 is an example in which two current sensorsandare included. The current sensorfor detecting the control reactor current IL of the control reactoris the same as the current sensorin the power conversion deviceof Embodiment 1, which detects the control reactor current IL of the control reactor. The rectifier circuit current Iin is the current output by the rectifier circuitand is the current right after the rectifier circuit.

18 FIG. 19 FIG. 18 FIG. 5 FIG. 5 FIG. 18 FIG. 2 FIG. 10 17 10 17 10 10 10 17 21 36 2 18 10 15 16 c shows the first controllerwith the rectifier circuit current Iin as the filter focusing target, andshows the second controllerwith a current ripple component ΔIin of the rectifier circuit current Iin as the filter focusing target. First, the first controllerof Embodiment 4 will be described. The first controllerof Embodiment 4 shown indiffers from the first controllerof Embodiment 1 shown inin that the rectifier circuit current Iin is input as the filter focusing targetto the subtractorof the second system control unitthat generates the second system command C*, and a current command Iin* of the rectifier circuit current Iin is input as the filter focusing target command. Other configurations are the same as the first controllerof Embodiment 1 shown in. Note that in, the phase voltage calculation unitand the filter voltage command generation unitdescribed inare omitted.

10 21 2 90 21 2 21 35 1 1 2 5 FIG. c c b The differences from the first controllerof Embodiment 1 shown inwill be mainly described. The subtractorgenerates a current deviation ΔIas the deviation between the rectifier circuit current Iin being the current of the filterand a command value of the current command Iin* being the target value of the rectifier circuit current Iin. Specifically, the subtractorgenerates the current deviation ΔIby subtracting the rectifier circuit current Iin from the current command Iin*. The reference sign of the current deviation generated by the subtractorin the first system control unitthat generates the first system command C* is denoted as ΔIto distinguish it from the current deviation ΔI.

24 2 2 2 10 1 1 35 2 2 36 21 37 2 1 10 d The damping feedback control unitoutputs the second command B* as the second system command C* based on the current deviation ΔI. The first controllergenerates the first command B* as the first system command C* by the first system control unitand generates the second command B* as the second system command C* by the second system control unit. The subtractorbeing the on-duty command generation unitgenerates the on-duty command D* by subtracting the second system command C* from the first system command C*. The operation after the generation of the on-duty command D* is the same as that of the first controller.

10 10 10 17 21 36 2 18 21 10 19 FIG. 9 FIG. 9 FIG. c c Next, the second controllerof Embodiment 4 will be described. The second controllerof Embodiment 4 shown indiffers from the fifth controllerof Embodiment 1 shown inin that the current ripple component ΔIin of the rectifier circuit current Iin is input as the filter focusing targetto the subtractorin the second system control unitthat generates the second system command C*, a current ripple component command ΔIin* being a command of the current ripple component ΔIin is input as the filter focusing target command, and a ripple component deviation ΔIrp is output from the subtractor. Other configurations are the same as the fifth controllerof Embodiment 1 shown in.

10 21 90 21 27 21 c c c The differences from the fifth controllerof Embodiment 1 will be described. The subtractorgenerates, as the ripple component deviation ΔIrp, the deviation between the current ripple component ΔIin, which is the ripple component in the current of the filter, that is, the rectifier circuit current Iin, and a command value of the current ripple component command ΔIin*, which is the target value of the current ripple component ΔIin. Specifically, the subtractorgenerates the ripple component deviation ΔIrp by subtracting the current ripple component ΔIin from the current ripple component command ΔIin*. Since the rectifier circuit current Iin contains a DC component, the current ripple component ΔIin is extracted through the high-pass filter. The current ripple component ΔIin is input to the subtractor. Since it is desirable that the rectifier circuit current Iin does not oscillate, the command value of the current ripple component ΔIin, that is, the command value of the current ripple component command ΔIin*, should be set to zero.

24 2 2 10 1 1 35 2 2 36 21 37 2 1 10 d 9 FIG. The damping feedback control unitoutputs the second command B* as the second system command C* based on the ripple component deviation ΔIrp. The second controllergenerates the first command B* as the first system command C* by the first system control unit, and generates the second command B* as the second system command C* by the second system control unit. The subtractorbeing the on-duty command generation unitgenerates the on-duty command D* by subtracting the second system command C* from the first system command C*. The operation after the generation of the on-duty command D* is the same as that of the fifth controllerof Embodiment 1 shown in.

10 17 21 36 2 18 10 10 10 17 21 36 2 18 c c 8 FIG. 5 FIG. 7 FIG. 8 FIG. 5 FIG. 7 FIG. 8 FIG. The controllerof Embodiment 4 in which the rectifier circuit current Iin is input as the filter focusing targetto the subtractorin the second system control unitthat generates the second system command C*, and the current command Iin* of the rectifier circuit current Iin is input as the filter focusing target commandcan be applied not only to the first controllershown inbut also to the controllersof Embodiment 1 shown in,, and. In the controllersshown in,, andof Embodiment 1, the rectifier circuit current Iin should be input as the filter focusing targetto the subtractorin the second system control unitthat generates the second system command C*, and the current command Iin* of the rectifier circuit current Iin should be input as the filter focusing target command.

10 17 21 36 2 18 10 10 10 17 21 36 2 18 21 c c c 8 FIG. 5 FIG. 7 FIG. 8 FIG. 5 FIG. 7 FIG. 8 FIG. The controllerof Embodiment 4 in which the current ripple component ΔIin of the rectifier circuit current Iin is input as the filter focusing targetto the subtractorin the second system control unitthat generates the second system command C*, and the current ripple component command ΔIin* being the command of the current ripple component ΔIin is input as the filter focusing target commandcan be applied not only to the first controllershown inbut also to the controllersof Embodiment 1 shown in,, and. In the controllersshown in,, andof Embodiment 1, the current ripple component ΔIin of the rectifier circuit current Iin should be input as the filter focusing targetto the subtractorin the second system control unitthat generates the second system command C*, and the current ripple component command ΔIin* being the command of the current ripple component ΔIin should be input as the filter focusing target command. Note that the output of the subtractorwill be the ripple component deviation ΔIrp.

50 50 50 5 The power conversion deviceof Embodiment 4 can prevent the breakage of the peripheral devices by reducing the outflow of the carrier ripple current, similarly to the power conversion devicesof Embodiment 1 and Embodiment 2. Further, by reducing the distortion of the power supply current Ips, component losses can be reduced, and a component with a small current rating can be applied. In addition, the power conversion deviceof Embodiment 4 can reduce the current distortion, so that the inductance of the control reactorcan be reduced.

50 2 55 55 55 91 2 6 64 64 91 90 55 55 55 91 9 10 91 91 3 1 26 10 90 90 17 17 18 50 90 9 55 55 55 91 10 18 17 90 90 r s t p n r s t a r s t As described above, the power conversion deviceof Embodiment 4 includes the rectifier circuitthat converts the input voltages (interphase voltage Vac) of the three-phase AC input from the AC input terminals,, andinto the DC voltage, the converterthat outputs the output voltage Vo set to the set voltage value from the DC voltage output from the rectifier circuit, the smoothing capacitorconnected between the positive-side converter output terminal (DC output terminal) and the negative-side converter output terminal (DC output terminal) of the converterfrom which the output voltage Vo is output, the filterdisposed between the AC input terminals,, and, and the converterand including the filter capacitor, and the controllerthat controls the converter. The converterincludes the switching elementthat is controlled with PWM by the control signal siggenerated on the basis of the carrier waveand the on-duty command D*. The controllerdesignates the current of the filter(rectifier circuit current Iin) or the ripple component of the current of the filter(current ripple component ΔIin) as the filter focusing target. It generates the on-duty command D* that reduces the difference between the detection value of the filter focusing targetand the target value of the filter focusing target (filter focusing target command). In the power conversion deviceof Embodiment 4, with this configuration, since the filterincluding the filter capacitoris disposed between the AC input terminals,, and, and the converter, and the controllergenerates the on-duty command D* that reduces the difference between the detection value and the target value (filter focusing target command) in the filter focusing target, which is the current of the filter(rectifier circuit current Iin) or the ripple component (current ripple component ΔIin) in the current of the filter, it is possible to reduce the carrier ripple current and to reduce the outflow of the carrier ripple current to the power supply.

20 FIG. 21 FIG. 20 FIG. 22 FIG. 20 FIG. 23 FIG. 120 50 91 90 10 is a diagram showing a configuration of a first refrigeration cycle apparatus according to Embodiment 5.is a diagram showing a configuration of a refrigerant circuit of, andis a diagram showing a configuration of an inverter of.is a diagram showing a configuration of a second refrigeration cycle apparatus according to Embodiment 5. In Embodiment 5, a refrigeration cycle apparatusin which the power conversion deviceincluding the converter, the filter, and the controlleraccording to Embodiment 1 to Embodiment 4 is mounted will be described.

120 110 120 120 The refrigeration cycle apparatusincludes a refrigerant circuitthat constitutes a refrigeration cycle in which a refrigerant circulates while changing in repeated processes of “compression”, “condensation”, “expansion”, and “evaporation”. Examples of the refrigeration cycle apparatusinclude an air conditioner and a refrigeration device. In the following description, an air conditioner as the refrigeration cycle apparatuswill be described as an example.

50 92 50 50 50 50 64 91 65 92 74 64 91 65 92 74 6 74 74 11 6 90 55 55 55 91 8 9 50 51 50 51 20 FIG. 23 FIG. 20 FIG. 20 FIG. 20 FIG. 20 FIG. 23 FIG. p p p n n n p n a r s t A first power conversion deviceof Embodiment 5 shown inis a power conversion device in which an inverteris added to the power conversion deviceof Embodiment 1 to Embodiment 4. A second power conversion deviceof Embodiment 5 shown inis the power conversion deviceof Embodiment 1 to Embodiment 4. In the first power conversion deviceof Embodiment 5 shown in, the DC output terminalof the converterand a DC input terminalof the inverterare connected by a positive-side power line, and the DC output terminalof the converterand a DC input terminalof the inverterare connected by a negative-side power line. In, the smoothing capacitorconnected between the positive-side power lineand the negative-side power lineand the voltage sensorfor detecting the output voltage Vo of the smoothing capacitorare omitted. Further, in, the filterdisposed between the AC input terminals,, and, and the converterand including the filter reactorand the filter capacitoris omitted. The first power conversion deviceof Embodiment 5 shown inis for an example of supplying three-phase AC power to a motorbeing an AC motor, and the second power conversion deviceof Embodiment 5 shown inis for an example of supplying DC power to the motorbeing a DC motor.

92 3 3 3 3 3 3 3 3 66 3 3 66 3 3 66 3 3 3 3 3 65 3 3 3 65 92 66 66 66 56 56 56 50 67 67 67 110 56 56 56 50 72 72 72 66 66 66 92 56 56 56 50 72 72 72 67 67 67 110 72 72 72 72 a f a b c d e f u a b v c d w e f a c e p b d f n u v w a b c a b c a b c u v w u v w a b c u v w a b c u v w The inverteris a bridge inverter circuit including, for example, six switching elementsto. The switching elementsandconnected in series are an arm of a u-phase of the three-phase AC, the switching elementsandconnected in series are an arm of a v-phase of the three-phase AC, and the switching elementsandconnected in series are an arm of a w-phase of the three-phase AC. An AC output terminalis connected to the connection point of the switching elementsand, an AC output terminalis connected to the connection point of the switching elementsand, and an AC output terminalis connected to the connection point of the switching elementsand. The collectors of the switching elements,, andare connected to the positive-side DC input terminal, and the emitters of the switching elements,, andare connected to the negative-side DC input terminals. The inverteroutputs three-phase AC power from the AC terminals,, andthrough output terminals,, andof the power conversion device. Input terminals,, andof the refrigerant circuitare connected to the output terminals,, andof the power conversion deviceby power lines,, and. Note that the reference signs for the power lines connecting the AC output terminals,, andof the inverterand the output terminals,, andof the power conversion deviceare also denoted by,, and. The reference signs for the power lines connected to the input terminals,, andof the refrigerant circuitare collectively denoted by a reference numeral, and,, andare used for distinction.

1 3 59 1 3 59 1 3 59 1 3 59 1 3 59 1 3 59 59 92 59 59 92 1 1 1 a a a b b b c c c d d d e e e f f f a f b a f A control signal sis input to the gate of the switching elementvia a control terminal, and a control signal sis input to the gate of the switching elementsvia a control terminal. Similarly, a control signal sis input to the gate of the switching elementvia a control terminal, and a control signal sis input to the gate of the switching elementvia a control terminal. A control signal sis input to the gate of the switching elementsvia a control terminals, and a control signal sis input to the gate of the switching elementsvia a control terminal. A reference numeralis collectively used for the control terminals of the inverter, andtoare used for distinction. The reference signs for the control signals input to the inverterare collectively referred to as sig, and are referred to as sto sfor distinction.

58 91 29 10 59 92 1 29 10 29 29 1 50 1 3 3 29 1 10 3 3 a b b a b a f b b a f The control terminalof the converterreceives a control signal sigla output from a drive circuiton the basis of the gate signal command G* output from the controller. The control terminalof the inverterreceives a control signal sigoutput from a drive circuiton the basis of a gate signal command Gi* output from the controller. The drive circuitand the control signal sigla are the drive circuitand the control signal sigof the power conversion deviceof Embodiment 1 to Embodiment 4. The control signal sigis a signal for controlling the ON state and the OFF state of the switching elementstoby, for example, PWM control. The drive circuitoutputs the control signal sigwhose voltage value is changed on the basis of the gate signal command Gi* output from the controller. The gate signal command Gi* is generated for each of the switching elementsto. As the gate signal command Gi*, a gate signal command for performing normal PWM control can be used.

120 108 101 102 103 104 105 102 101 110 110 101 103 105 104 105 103 110 105 107 101 102 103 104 106 105 107 50 101 102 103 104 106 101 51 101 51 50 50 51 51 51 101 51 101 101 a a a An air conditioner, which is an example of a refrigeration cycle apparatus, is connected by a refrigerant pipein the order of a compressor, a four-way valve, an outdoor heat exchanger, an expansion device, an indoor heat exchanger, the four-way valve, and the compressorto form the refrigeration cycle, that is, the refrigerant circuit. That is, in the refrigerant circuit, the compressor, a condenser (the outdoor heat exchangeror the indoor heat exchanger), the expansion device, and an evaporator (the indoor heat exchangeror the outdoor heat exchanger) are connected in a loop by the refrigerant pipe. In the refrigerant circuit, the indoor heat exchangeris an indoor part, and the compressor, the four-way valve, the outdoor heat exchanger, and the expansion deviceare an outdoor part. An indoor unit of the air conditioner includes the indoor heat exchangerof the indoor part. An outdoor unit of the air conditioner includes the power conversion device, and the compressor, the four-way valve, the outdoor heat exchanger, and the expansion deviceof the outdoor part. The compressorincludes the motorand compression components. The motoris supplied with electric power from the power conversion deviceand is rotationally driven. The power conversion devicesupplies electric power to the motorto rotationally drive the motor. The motoris connected to the compression components, and the motorand the compression componentsconstitute the compressorthat compresses the refrigerant.

102 101 103 105 101 Next, the operation of the air conditioner will be described by taking a cooling operation as an example. Note that, when the cooling operation is performed, it is assumed that the four-way valveswitches the flow path in advance such that the refrigerant discharged from the compressoris directed to the outdoor heat exchangerand the refrigerant flowing out from the indoor heat exchangeris directed to the compressor.

51 101 50 101 101 51 101 101 103 102 103 103 104 105 105 105 105 101 102 103 105 103 105 a The motorof the compressoris rotationally driven by the power conversion device, whereby the compression componentsof the compressorconnected to the motorcompress the refrigerant, and the compressordischarge a high-temperature and high-pressure refrigerant. The high-temperature and high-pressure refrigerant discharged from the compressorflows into the outdoor heat exchangervia the four-way valve, and exchanges heat with the outside air in the outdoor heat exchangerto radiate heat. The refrigerant flowing out of the outdoor heat exchangeris expanded and decompressed by the expansion deviceto become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and flows into the indoor heat exchanger. The refrigerant that has flowed into the indoor heat exchangerexchanges heat with the air in the space to be air-conditioned, evaporates, becomes a low-temperature and low-pressure gas refrigerant, and flows out of the indoor heat exchanger. The gas refrigerant flowing out of the indoor heat exchangeris sucked into the compressorvia the four-way valveand compressed again. The above operation is repeated. When the air conditioner performs the cooling operation, the outdoor heat exchangerfunctions as the condenser, and the indoor heat exchangerfunctions as the evaporator. When the air conditioner performs the heating operation, the outdoor heat exchangerfunctions as the evaporator and the indoor heat exchangerfunctions as the condenser, which is the reverse of the cooling operation.

20 FIG. 21 FIG. 23 FIG. 23 FIG. 50 92 50 101 120 51 101 50 101 120 50 64 64 91 110 56 56 51 101 110 110 67 67 67 67 110 56 56 50 74 74 64 64 91 56 56 50 74 74 6 74 74 11 6 120 p n a b a b a b a b p n p n a b p n p n a Note that, althoughshows an example in which the power conversion devicein which the inverteris added to the power conversion deviceof Embodiment 1 to Embodiment 4 is applied to the power conversion device that supplies power to the compressorof the air conditioner as an example of the refrigeration cycle apparatus, this is not a limitation. When the motorof the compressoris a DC motor, as shown in, the power conversion deviceof Embodiment 1 to Embodiment 4 can be applied to a power conversion device that supplies electric power to the compressorof the refrigeration cycle apparatus. The power conversion deviceshown inoutputs DC power outputted from the DC output terminaland the DC output terminaof the converterto the refrigerant circuitvia the output terminalsand. When the motorof the compressorin the refrigerant circuitis a DC motor, the refrigerant circuithas two input terminalsand. The input terminalsandof the refrigerant circuitare connected to output terminalsandof the power conversion deviceby the positive-side power lineand the negative-side power line, respectively. Note that the power lines connecting the DC output terminalsandof the converterand the output terminalsandof the power conversion deviceare referred to as the positive-side power lineand the negative-side power line. The smoothing capacitoris connected between the positive-side power lineand the negative-side power line. Note that, in, the voltage sensorfor detecting the output voltage Vo being the voltage of the smoothing capacitoris omitted. In addition, it is needless to say that the refrigeration cycle apparatuscan be applied to a heat pump device, a refrigeration device, and other refrigeration cycle apparatuses in general, in addition to the air conditioner.

120 110 101 103 105 104 105 103 108 50 101 50 2 55 55 55 91 2 6 64 64 91 90 55 55 55 91 8 9 10 91 50 92 91 10 8 55 55 55 9 120 90 8 9 55 55 55 91 8 55 55 55 9 50 r s t p n r s t r s t r s t r s t As described above, the refrigeration cycle apparatusof Embodiment 5 includes the refrigerant circuitin which the compressor, the condenser (the outdoor heat exchangeror the indoor heat exchanger), the expansion device, and the evaporator (the indoor heat exchangeror the outdoor heat exchanger) are connected in a loop by the refrigerant pipe, and the power conversion devicethat drive the compressorby supplying electric power to the compressor. The power conversion deviceincludes the rectifier circuitthat converts the input voltages (interphase voltage Vac) of the three-phase AC input from the AC input terminals,, andinto the DC voltage, the converterthat outputs the output voltage Vo set to the set voltage value, from the DC voltage output from the rectifier circuit, the smoothing capacitorconnected between the positive-side converter output terminal (DC output terminal) and the negative-side converter output terminal (DC output terminal) of the converterfrom which the output voltage Vo is output, the filterdisposed between the AC input terminals,, and, and the converterand including the filter reactorand the filter capacitor, and the controllerthat controls the converter. In addition, the power conversion devicemay include the inverterthat converts the DC output voltage Vo output from the converterinto the AC voltage and is controlled by the controller. The filter reactoris disposed closer to the AC input terminals,, andthan the filter capacitor. In the refrigeration cycle apparatusof Embodiment 5, with this configuration, the filterincluding the filter reactorand the filter capacitoris disposed between the AC input terminals,, and, and the converter, and the filter reactoris disposed closer to the AC input terminals,, andthan the filter capacitorin the power conversion device. Therefore, the carrier ripple current can be reduced, and the outflow of the carrier ripple current to the power supply can be reduced.

Note that, although various exemplary embodiments and examples are described in the present disclosure, various features, aspects, and functions described in one or more embodiments are not inherent in a particular embodiment and can be applicable alone or in their various combinations to each embodiment. Accordingly, countless variations that are not illustrated are envisaged within the scope of the art disclosed in the disclosure. For example, the case where at least one component is modified, added or omitted, and the case where at least one component is extracted and combined with a component in another embodiment are included.

Although the preferred embodiments and the like have been described in detail above, the above-described embodiments and the like is not a limitation, and various modifications and substitutions can be made to the above-described embodiments and the like without departing from the scope described in the claims.

Hereinafter, various aspects of the present disclosure will be collectively described as supplementary notes.

The power conversion device includes the rectifier circuit to convert an input voltage of the three-phase AC input from the AC input terminals into a DC voltage, the converter to output an output voltage set to a set voltage value from the DC voltage output from the rectifier circuit, the smoothing capacitor connected between the positive-side converter output terminal and the negative-side converter output terminal of the converter from which the output voltage is output, the filter disposed between the AC input terminals and the converter and including the filter capacitor, and the controller to control the converter. The converter includes the switching element that is controlled with PWM by a control signal generated on the basis of the carrier wave and the on-duty command. The controller designates any one of the voltage of the filter, the current of the filter, the ripple component in the voltage of the filter, and the ripple component in the current of the filter as the filter focusing target and generates the on-duty command for reducing a difference between the detection value of the filter focusing target and the target value of the filter focusing target.

The power conversion device according to Supplementary Note 1, wherein the filter incudes the filter reactor, and the filter reactor is connected between the positive-side rectifier circuit output terminal of the rectifier circuit and one end of the filter capacitor connected to the positive-side converter input terminal of the converter.

The power conversion device according to Supplementary Note 1, wherein the filter incudes the filter reactor, and the filter reactor is connected between the AC input terminal and the rectifier circuit input terminal of the rectifier circuit.

The power conversion device according to Supplementary Note 3, wherein the filter reactor constitutes the common mode choke coil.

The power conversion device according to any one of

Supplementary Notes 1 to 4, wherein the controller includes the first system control unit to generate the first system command for reducing a difference between the detection value of the voltage of the smoothing capacitor and the target value of the voltage of the smoothing capacitor, the second system control unit to generate the second system command for reducing a difference between the detection value of the filter focusing target and the target value of the filter focusing target, and the on-duty command generation unit to generate the on-duty command based on the first system command and the second system command.

The power conversion device according to Supplementary Note 5, wherein the filter focusing target is the voltage of the filter capacitor in the filter, the target value of the filter focusing target is the command value of the voltage of the filter capacitor, and the controller includes the phase voltage calculation unit to calculate phase voltages of the three phases of the three-phase AC from the interphase voltages that are voltages between any two of the three AC input terminals to which the three-phase AC is input, and the filter voltage command generation unit to generate the phase voltage deviation obtained by subtracting the minimum phase voltage from the maximum phase voltage as the command value of the voltage of the filter capacitor, when the maximum phase voltage is a phase voltage that is the highest among the phase voltages of the three phases, and the minimum phase voltage is a phase voltage that is the lowest among the phase voltages of the three phases.

The power conversion device according to Supplementary Note 5, wherein the filter focusing target is the input current input to the filter, and the target value of the filter focusing target is the command value of the input current.

The power conversion device according to Supplementary Note 5, wherein the filter focusing target is the ripple component of the filter capacitor voltage being the voltage of the filter capacitor in the filter, the target value of the filter focusing target is the command value of the ripple component of the filter capacitor voltage, and the controller includes the subtractor to subtract the ripple component of the filter capacitor voltage from the command value of the ripple component of the filter capacitor voltage, and the command value of the ripple component of the filter capacitor voltage is set to zero.

The power conversion device according to Supplementary Note 5, wherein the filter focusing target is the ripple component of the input current input into the filter, the target value of the filter focusing target is the command value of the ripple component of the input current, and the controller includes the subtractor to subtract the ripple component of the input current from the command value of the ripple component of the input current, and the command value of the ripple component of the input current is set to zero.

The power conversion device according to any one of Supplementary Notes 5 to 9, wherein the first system control unit includes one or more of the proportional output unit that performs proportional control, the integrator that performs integral control, and the differentiator that performs differential control.

The power conversion device according to any one of Supplementary Notes 5 to 10, wherein the second system control unit includes one or more of the proportional output unit that performs proportional control, the integrator that performs integral control, and the differentiator that performs differential control.

The power conversion device according to any one of Supplementary Notes 5 to 9, wherein the first system control unit includes one or more of the proportional output unit that performs proportional control, the integrator that performs integral control, and the differentiator that performs differential control, the second system control unit includes the proportional output unit, and the on-duty command generation unit includes one or more of the proportional output unit, the integrator, and the differentiator.

The power conversion device according to Supplementary Note 5 or 6, wherein the filter focusing target is the voltage of the filter capacitor in the filter, a frequency for controlling the converter is the control frequency, a number obtained by dividing the control frequency by the frequency of the three-phase AC is the division number, and the controller includes, in the second system control unit or the on-duty command generation unit, the phase change feedback control unit to perform proportional processing and integral processing on the input data input from the first terminal and output the output data changed by the predetermined set phase from the second terminal. The phase change feedback control unit includes the same number of integrators as the division number, the selector that selects an integrator to which data is input, the selector that selects an integrator that outputs data having a phase different from the input data by the set phase, and the proportional output unit on the data path between the first terminal and the second terminal.

The power conversion device according to Supplementary Note 5 or 8, wherein the filter focusing target is the ripple component of the voltage of the filter capacitor in the filter, a frequency for controlling the converter is the control frequency, a number obtained by dividing the control frequency by the frequency of the three-phase AC is the division number, and the controller includes, in the second system control unit or the on-duty command generation unit, the phase change feedback control unit to perform proportional processing and integral processing on the input data input from the first terminal and output the output data changed by the predetermined set phase from the second terminal. The phase change feedback control unit includes the same number of integrators as the division number, the selector that selects an integrator to which data is input, the selector that selects an integrator that outputs data having a phase different from the input data by the set phase, and the proportional output unit on the data path between the first terminal and the second terminal.

The power conversion device according to any one of Supplementary Notes 5 to 11, 13, and 14, wherein the controller, in the first system control unit, includes the feedback control unit that generates the on-duty command such that the input current of the three-phase AC becomes a rectangular wave current.

The power conversion device according to Supplementary Note 12, wherein the controller, in the on-duty command generation unit, includes the feedback control unit that generates the on-duty command such that the input current of the three-phase AC becomes a rectangular wave current.

The power conversion device according to any one of Supplementary Notes 1 to 16, wherein the filter includes the filter reactor, and the resonant frequency depending on the filter capacitor and the filter reactor in the filter is set to be equal to or higher than a frequency 18 times the frequency of the three-phase AC and equal to or lower than half of the frequency of the carrier wave.

The power conversion device according to any one of Supplementary Notes 1 to 17, wherein the converter is any one of the step-down converter, the step-up converter, and the step-up/step-down converter.

The power conversion device according to any one of Supplementary Notes 1 to 18, further includes the inverter to convert the output voltage of a DC output from the converter into an AC voltage. The controller controls the inverter.

The refrigeration cycle apparatus includes the refrigerant circuit in which the compressor, the condenser, the expansion device, and the evaporator are connected in a loop by the refrigerant pipe, and the power conversion device according to any one of Supplementary Notes 1 to 19 that drives the compressor by supplying electric power to the compressor.